资源环境科技发展态势分析平台

Changes in the relationship between interannual variation of spring (March-April-May) surface air temperature (SAT) over eastern Eurasia (SAT_EA) and Eurasian snow during 1972-2009 are investigated. The results show that the interannual variation in SAT_EA is significantly correlated with Eurasian snow cover anomalies (SCA) over two key regions, which include the western (SCAW) and eastern (SCAE) parts of the Eurasian continent. A pronounced climate shift of SAT_EA is observed around the late 1980s, and therefore, the data are divided into two subperiods, that is, 1972-1987 (P1) and 1988-2009 (P2). Examinations show that the relationship between SAT_EA and SCAW is impacted by the Arctic Oscillation. In contrast, the relationship between SCAE and the SAT_EA is Arctic Oscillation independent and is significantly increased from P1 to P2. Further analysis shows that the increased correlation between SAT_EA and SCAE from P1 to P2 cannot be well explained by the snow-related surface heat flux. A wave train-like anomalous circulation plays an important role in enhancing their relationship through intensified wind-induced heat advection in P2, which causes reduced snow and increased SAT_EA. A lead-lag regression analysis of the SCAE and the circulation anomalies indicates that the changes of the SCAE and SAT_EA are mainly responses to atmospheric circulation anomalies that occur 2months before spring. Numerical experiments that use a linear baroclinic model indicate that the snow anomalies around Lake Baikal may impact the variation of SAT_EA through modulating atmospheric circulation over the East Asia-North Pacific area.